Effect of bacterial endotoxin on the phagocytic activity of the reticulo-endothelial system in rabbits of different age

Stimulation of the phagocytic activity of the reticulo-endothelial system with bacterial endotoxin was studied in newborn rabbits in the period in which they do not actively form antibodies to bacterial antigens. A markedly accelerated clearance of colloidal carbon from the blood was found in five-day-old rabbits (tested by the technique of Biozzi, Benacerraf and Halpern 1953) when relatively high doses of endotoxin were used. It is assumed that the increased resistance to infection which may be elicited in young animals in that period is due to stimulation of cellular defence mechanisms. By comparison of the stimulating effect of endotoxin on phagocytosis in five-day-old, one-month-old and adult rabbits it was found that the phagocytic cells of the R.E.S. are more susceptible to the effect of endotoxin in adults than in newborns. This difference is evident from comparisons of the phagocytic indices K and the corrected phagocytic indices α in three age groups of rabbits stimulated with different doses of endotoxin. The possible mechanism and cause of differences in sensitivity of young and adult individuals is discussed.     

Calpain and calpastatin levels in different organs of the rabbit

1. The levels of Ca-independent and Ca-dependent proteolytic activity as well as the activities of calpains and calpastatin in different organs of the rabbit was examined at various developmental stages. 2. Calpain and calpastatin levels were highest in the lung and in the kidney. 3. In all organs examined except the thymus the total level of calpain was higher than that of calpastatin. 4. In the thymus the levels of calpains and calpastatin decreased markedly with age.     

Changes in the composition of fatty acids in blood plasma lipids and in various organs in traumatic shock

The composition of fatty acids of the total lipids of the myocardium, lungs, liver, intestine, adipose tissue, and blood plasma was studied during traumatic shock reproduced in dogs by crush of soft tissues of the hip. The formation of the shock process was accompanied by a rise in the percentage content of linoleic and arachidonic acids in the blood plasma and some organs; a close correlation existed between the linoleic acid content in the adipose tissue and the blood. Oleic acid deficiency was revealed in the lipids of the organs under study.     

Change in the contractile activity of the rabbit myocardium as a result of burn shock of different duration]

Experiments were carried out on the papillary muscles prepared from the rabbit heart 10, 60 or 180 minutes after exposure of the animals to thermal burn. Isometric tension in the changing stimulation frequency of the preparation (the range being 0.1-2.0 Hz) and in post-stimulating potentiation was recorded. It was shown that the disturbance degree of the myocardial contractile activity caused by the burn rose depending on increased shock duration. It was evidenced by the following findings: in all the papillary muscles prepared 3 hours after burn and in 50% of the preparations taken one hour after the injury the "biphasic" dependence frequency power (F-P) peculiar to healthy myocardium changed to "monophasic" one (contraction amplitude progressively decreased on the frequency growing), and poststimulating potentiation, absent in the normal myocardium state, appeared. Within 10-minute shock duration only several preparations revealed poststimulating potentiation, F-P changes being absent. Normal rhythmoinotropic relationships in the myocardium restored under the influence of two-fol increase of (Ca2+)o or under prolonged (3-4 hours) perfusion of the preparation with normal Tyrode's solution. The changes observed in the myocardium rhythmoinotropic relationships produced by the burn shock were similar to those occurred as a result of the calcium canals block by the compound D-600.     

Microcirculatory disorders in the connective tissue structures of certain organs in traumatic shock with acute hemorrhage]

The present work is a fragment of the author's complex study of replantation of an extremity in experiment. Experiments on reproduction of the model of traumatic shock with acute loss of blood under conditions of muscle relaxation proposed by Yu. V. Kiprenski were performed in 15 dogs and 10 cats. It was established that in animals dead as a result of shock there appeared severe disorders of microcirculation in tissues and organs. They were characterized by a pronounced spasm of the vessels of the arteriolar link and dilatation of the venular and lymph collectors of the microcirculation bed. Simultaneously a great number of arterio-venular anastomoses were opened through which the arterial blood was shunted partly to avoid constricted capillaries. In the vessels of the venular link of the microcirculatory bed there appeared aggregations of formed elements of blood and microemboles. In absence of specific complex therapy, as it was in our experiments, the animals die of shock within the period from 17 min to 5 hour 20 min.